Ten males and seven females were collected from the Alaska Peninsula and Aleutian Islands in 2003 and installed in a large outdoor pen at the Seward center as part of a federally funded captive breeding program.

Researchers have observed the sea ducks for a year. To help get the ducks in the mood this spring, their 25-foot-by-60-foot pen was converted into something more cozy, with tundra grasses, moss, pebbles, driftwood and natural barriers for increased privacy.

Then, the researchers watched and waited.

"We saw courtship behavior, such as mating displays including head throws, bill lifts - typical eider mating behavior that we know of from the wild," said Tuula Hollmen, the center's eider program manager.

The ducks did more body bumps, waddling and wing flapping - all encouraging signs that the sexes were getting along swimmingly.

The males acted interested. They called out to the females, who appeared willing, some even preparing for family by eating more and bulking up. One had a distended abdomen indicating her ovaries were gearing up for motherhood. One went so far as to place some down feathers in a nest.

"I would say that the females were more ready than the males," said Heidi Weingartz, the center's avian curator. "If it was up to the girls, there would be a lot more babies around."

In the end, the males apparently were a bit shy. No olive-colored eggs were produced. The males - which in breeding plumage have a black back, white shoulders, chestnut breast and belly and a white head with a green tuft and black eye patches - reverted to an ordinary brown.

Weingartz and Hollmen are optimistic about trying again next spring.

"This is totally new, breeding this particular species in captivity. ... They already went way beyond our expectations this year," Weingartz said. "It is very difficult to figure out what it was that made them happy but not happy enough to breed."

The captive breeding program was launched last year to learn more about Steller's eiders in hopes of increasing their chances of surviving, if not in the wild then in captivity, Hollmen said.

"We like to think we can save the species, but we also prepare for the worst by establishing these techniques now so they are available if they are needed," she said.

There are about 220,000 Steller's eiders worldwide, with fewer than 500 breeding pairs in Alaska. Biologists aren't sure why the numbers worldwide have fallen by as much as 50 percent in 30 years.

Steller's eiders historically have bred in northern and western Alaska, but now have nearly disappeared from most nesting sites in the state. Their current primary nesting site is a portion of the central Arctic coastal plain near Barrow. Larger numbers nest in northern Russia.

The majority of Steller's eiders winter in Alaska from the eastern Aleutian Islands to the lower Cook Inlet.

The birds were once common on the Yukon-Kuskokwim Delta but in the past few years there has been just one documented nesting site, Hollmen said. Before the 1960s, there may have been as many as 4,000 pairs nesting in the delta, according to the U.S. Fish and Wildlife Service.

The reasons for the decline aren't known.

The Sealife Center's captive breeding program is part of a larger eider program begun in 2001 to research Steller's and spectacled eiders, both listed as threatened under the federal Endangered Species Act. For fiscal 2004, the center received $818,000 in federal funds to research eiders.